Short Answer
It is the distribution of _ atoms in the spiral arms that is measured with 21- cm radio maps.
Correct Answer:

Verified
Correct Answer:
Verified
Related Questions
Q8: Contrast the observed visible mass of the
Q9: The Milky Way is similar in many
Q10: Which is the correct description of the
Q11: Most of the new star formation in
Q12: The spherical distribution of the globular clusters
Q14: Our Sun lies about 30,000 light-years out
Q15: The two stellar populations are extremes, but,
Q16: What is the mass of the black
Q17: Which sequence of formation is most likely
Q18: Based on his star counts, Herschel placed